1. Field of the Invention
The present invention relates generally to Visible Light Communication (VLC), and more particularly, to a VLC method and system to which a Media Access Control (MAC) protocol is applied.
2. Description of the Related Art
The recent improvement of luminous efficiency and price decrease for Light Emitting Diodes (LEDs) have recently contributed to the popularization of LEDs in the special lighting market for portable devices, displays, automobiles, traffic lights and electronic display boards, as well as in the conventional lighting market for fluorescent lamps and incandescent lamps. In addition, due to the exhaustion of Radio Frequency (RF) frequencies, the possible interference among different wireless communication technologies, the increasing demand for communication security, and the advent of ultrahigh-speed Ubiquitous communication environments based on the 4th Generation (4G) wireless technology, there has been an increased interest in optical wireless technologies, which are complementary to RF technologies. Accordingly, extensive research on visible light wireless communication based on visible light LEDs is being conducted in many companies and laboratories.
VLC that delivers information using visible light beams makes it possible to accurately know information coverage not only because it is secure, has a wide band and can be freely used without regulations, but also because users can observe the place to which the light arrives and the direction along which the light progresses. Hence, VLC can offer reliable security and low power consumption. In light of these and other advantages, VLC can be applied even in airplanes where the use of RF is prohibited, and can also provide additional information services based on electronic display boards.
When the visible light is used for communications, a protocol for efficiently managing communication channels is required. The well-known short-range wireless communication protocols include wireless Local Area Network (LAN) and Infrared Data Association (IRDA). However, communication protocols used in wireless LAN and IRDA are unsuitable for VLC channels.
In wireless LAN, it is provided that an Access Point (AP) and Mobile Nodes (MNs) connected thereto should uniformly occupy resources without priorities. Therefore, the complicated communication algorithm, which is applied to the AP on which communication traffic is concentrated, is also applied to the MNs, which is undesirable since the MNs must be small and lightweight.
IRDA, which is designed mainly for point-to-point access, may not support a medium access technique when a plurality of MNs desire to access channels.
Therefore, a need exists in the art to develop a VLC protocol that can ensure efficient and stable communication.